The Science Behind The Evolution of Traits - Could you suddenly shoot webs due to a genetic mutation?
Introduction
What if suddenly we undergo a genetic mutation and our eyes turn black or we grow another limb? Wouldn’t that be something that is worth turning into a movie… The real question is: Is it possible? Many claim that mutation often results in the formation of major innovations or a very rare new trait. However, mutations actually show they only result in variations in pre-existing traits, traits that organisms already possess, and cannot result in the origin of novel traits. Even when we talk about ‘beneficial mutations’ that have led into the evolution of new mechanisms or traits in an organism, the way it works is the opposite of what we think. Beneficial mutations cannot account for the origin of novel traits but instead they cause the loss of or slight variation in pre-existing traits. That’s equivalent to a person who has suddenly lost all their money saying, “I’ve not lost money; I’ve just gained poverty!”. In the same way, an organism doesn’t gain novel traits needed to evolve into something else, instead, organisms lose traits or develop variations in pre-existing traits.
What about gene duplication, “new” genes and functions?
Evolutionists think that gene duplication allows free mutation of the new duplicated gene and gain new functions because the original copy of the gene can still perform the original function. Let’s look at the example of RNASE1 and RNASE1B in monkeys. The diet of most monkeys consists of fruit and insects; however, the colobine monkeys predominantly eat leaves. These monkeys have a special foregut that harbors symbiotic bacteria that help in the digestion of the leaves. RNASE1 is a digestive enzyme in colobines that breaks down RNA from the bacteria in the foregut. This results in the efficient recycling of phosphorus and nitrogen that are used in the production of the monkey’s own proteins and nucleic acids like DNA and RNA. It has been shown that some colobines have two RNASE genes—RNASE1 and RNASE1B. RNASE1B is proposed to be a duplication of the gene RNASE1. There are several differences in the genes and the proteins produced, however, the function remains the same. Both enzymes break down RNA, but the changes in RNASE1B allow it to break down RNA in more acidic conditions such as those found in the foregut of the monkeys. The differences caused by mutations in the RNASE1B gene appear to enhance the pre-existing function of the original RNASE1 gene, resulting in adaptation, and do not represent the type of mutation necessary for the origin of novel traits.
Do Beneficial Mutations Exist?
It is always interesting to refer to the stereotypes in science. The word ‘mutation’ would usually be associated with bad stuff or the development of a new disorder in a person but there could also be beneficial mutations. It is more appropriate to say that some mutations have beneficial outcomes in certain environments. Mutations are context dependent, meaning their environment determines whether the outcome of the mutation is beneficial. One well-known example of a proposed beneficial mutation is antibiotic resistance in bacteria. In an environment where antibiotics are present, mutations in the bacterial DNA allow the bacteria to survive. However, these same mutations come at the cost of damaging the normal functions of the bacteria (such as the ability to break down nutrients). If the antibiotics are removed, the antibiotic resistant bacteria typically do not fare as well as the normal (or wild-type) bacteria that have not been affected by mutations. Thus, the benefit of any given mutation is not an independent quality, but rather a dependent quality based on the environment.
Beneficial Mutations That Humans Are Undergoing Right Now
Most random genetic changes caused by evolution are neutral, and some are harmful, but a few turn out to be positive improvements. These beneficial mutations are the raw material that may, in time, be taken up by natural selection and spread through the population.
Apolipoprotein AI-Milano
All humans have a gene for a protein called Apolipoprotein AI, which is part of the system that transports cholesterol through the bloodstream. Apo-AI is one of the high-density lipoproteins, already known to be beneficial because they remove cholesterol from artery walls. But a small community in Italy is known to have a mutant version of this protein, named Apolipoprotein AI-Milano, or Apo-AIM for short. Apo-AIM is even more effective than Apo-AI at removing cholesterol from cells and dissolving arterial plaques, and additionally functions as an antioxidant, preventing some of the damage from inflammation that normally occurs in arteriosclerosis. People with the Apo-AIM gene have significantly lower levels of risk than the general population for heart attack and stroke, and pharmaceutical companies are looking into marketing an artificial version of the protein as a cardioprotective drug. There are also drugs in the pipeline based on a different mutation, in a gene called PCSK9, which has a similar effect. People with this mutation have as much as an 88% lower risk of heart disease.
Increased bone density
One of the genes that governs bone density in human beings is called low-density lipoprotein receptor-related protein 5, or LRP5 for short. Mutations which impair the function of LRP5 are known to cause osteoporosis. But a different kind of mutation can amplify its function, causing one of the most unusual human mutations known. This mutation was first discovered fortuitously, when a young person from a Midwest family was in a serious car crash from which they walked away with no broken bones. X-rays found that they, as well as other members of the same family, had bones significantly stronger and denser than average. (One doctor who’s studied the condition said, “None of those people, ranging in age from 3 to 93, had ever had a broken bone.”) In fact, they seem resistant not just to injury, but to normal age-related skeletal degeneration. Some of them have benign bony growths on the roof of their mouths, but other than that, the condition has no side effects – although, as the article notes dryly, it does make it more difficult to float. As with Apo-AIM, some drug companies are researching how to use this as the basis for a therapy that could help people with osteoporosis and other skeletal diseases.
Malaria resistance
The classic example of evolutionary change in humans is the hemoglobin mutation named HbS that makes red blood cells take on a curved, sickle-like shape. With one copy, it confers resistance to malaria, but with two copies, it causes the illness of sickle-cell anemia. This is not about that mutation. As reported in 200, Italian researchers studying the population of the African country of Burkina Faso found a protective effect associated with a different variant of hemoglobin, named HbC. People with just one copy of this gene are 29% less likely to get malaria, while people with two copies enjoy a 93% reduction in risk. And this gene variant causes, at worst, a mild anemia, nowhere near as debilitating as sickle-cell disease.
Reduced need for sleep
People often describe themselves as “night owls” or “early birds,” but people with a mutation in the DEC2 gene, which plays a crucial role in regulating sleep, can enjoy the benefits of both thanks to their reduced need for sleep. Although eight hours is the most common definition of a full night’s rest, scientists have long attested that this figure can vary based on a person’s age, health, and environment, suggesting seven to nine hours as a more reasonable estimate. However, some people with a DEC2 mutation can get by on just four hours of sleep and still feel refreshed. A 2018 study found that DEC2 helps regulate your circadian rhythm (aka your body’s “clock”), but when weakened by this gene mutation, it causes an overproduction of orexin, a hormone that maintains wakefulness. So if you’re ever frustrated there aren’t more hours in the day, feel free to blame your nonmutated DEC2 gene.
Conclusion
While not many of us would think of dramatic scenarios where we suddenly mutate to have scary traits like Peter after getting stressed out, it is safe to say that those dramatic changes are not possible for us in real life, though you could say for his case it was a development of pre-existing traits of the creature that bit him; a spider. It is important for us to understand how genetic mutations can give both harmful and beneficial effects to a population and how we can explore ways to make use of these beneficial evolution in nature for the sake of improving healthcare and the environment.
References
brooke (2025). 5 Genetic mutations that are actually helpful. [online] Interesting Facts. Available at: https://interestingfacts.com/beneficial-genetic-mutations/.
Lee, A. (2011). 4 Beneficial evolutionary mutations that humans are undergoing right now. [online] Big Think. Available at: https://bigthink.com/surprising-science/evolution-is-still-happening-beneficial-mutations-in-humans/
Purdom, D.G. (2020). Beneficial mutations. [online] Answers in Genesis. Available at: https://answersingenesis.org/genetics/epigenetics/what-about-beneficial-mutations/
This article was prepared by Ulya Ammar (University of Edinburgh).
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